Are you really suggesting that it's not possible for you write an independent implementation of an algorithm from the version you once read? Is this sort of "clean room" approach typical? It strikes me as absurdly cautious.
Besides, I just don't feel like it's fair to the R copyright authors. They worked hard to produce an implementation and they copylefted it, and I heavily relied on their implementation in order to reimplement it myself.
According to the United States Copyright Office[1], the algorithm itself can't be copyrighted, so that's why I wrote a high-level description of the algorithm.
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[1] "Copyright protection is not available for ideas, program logic, algorithms, systems, methods, concepts, or layouts."
But suppose you decide to reimplement the algorithm now, months later (based only on the notes you wrote on Wikipedia). I'm not a lawyer, but I would say that's almost certainly independent, unless you have extraordinary memory.